The concept of OpenFlow (OpenFlow), which was first introduced by Professor Nick Mckeown at Stanford University and later became a subproject of a Global Environment for Network Innovations (GENI) plan, is an open protocol standard supported by The Stanford Clean Slate Program. In OpenFlow, a control function is separated from a network device, a flow table structure is maintained in the network device, and a data packet is forwarded according to a flow table, where generation, maintenance, and configuration of the flow table are managed by a controller. In this architecture in which control is separated from forwarding, the controller may flexibly manage and configure a network resource in a forwarding link.
The OpenFlow mainly includes two parts: a switch and a controller. The switch forwards a data packet according to a flow table, and represents a data forwarding plane; the controller implements a management and control function using a global network view, and represents a control plane. For the switch, if a processing capability of the switch deteriorates, quality of service forwarding cannot be ensured, which even leads to a service interruption or a failure to respond to a new service. For example, when a flow table capacity of a switch in a service link reaches a storage upper limit of the switch, a new flow entry cannot be stored, that is, a new service cannot be processed, causing a network to be in a false saturated state and a waste of resources. As shown in FIG. 1, after a flow table of a switch 1 is full, a new flow service that passes through the switch 1 cannot be established, and at the same time, a storage capacity of a flow table of another switch may still be in a lower level. Therefore, flow table resources in an entire network are not properly used, resulting in a waste of network resources.
In conclusion, after a flow table of a switch in a service processing link is fully loaded, the switch cannot store a new flow entry or further process a new service, resulting in a waste of network resources.